#! @perl@ -w

use strict;
use File::Basename;

#print STDERR "FOO: @ARGV\n";

die unless defined $ENV{"NIX_OTHER_STORES"};
my @remoteStores = split ':', $ENV{"NIX_OTHER_STORES"};


sub findStorePath {
    my $storePath = shift;
    
    my $storePathName = basename $storePath;
    #print STDERR "GET $storePath\n";
    
    foreach my $store (@remoteStores) {
        # Determine whether $storePath exists by looking for the
        # existence of the info file, and if so, get store path info
        # from that file.  This rather breaks abstraction: we should
        # be using `nix-store' for that.  But right now there is no
        # good way to tell nix-store to access a store mounted under a
        # different location (there's $NIX_STORE, but that only works
        # if the remote store is mounted under its "real" location).
        my $infoFile = "$store/var/nix/db/info/$storePathName";
        my $storePath2 = "$store/store/$storePathName";
        if (-f $infoFile && -e $storePath2) {
            #print STDERR "FOUND IN $infoFile\n";
            return ($infoFile, $storePath2);
        }
    }
}


if ($ARGV[0] eq "--query-paths") {
    # !!! not implemented yet; needed for `nix-env -qas'
}


elsif ($ARGV[0] eq "--query-info") {
    shift @ARGV;
    
    foreach my $storePath (@ARGV) {

        (my $infoFile) = findStorePath $storePath;
        #print STDERR "XXX $infoFile\n";
        
        my $deriver = "";
        my @references = ();

        open INFO, "<$infoFile" or die "cannot read info file $infoFile\n";
        while (<INFO>) {
            chomp;
            #print STDERR "GOT $_\n";
            /^([\w-]+): (.*)$/ or die "bad info file";
            my $key = $1;
            my $value = $2;
            if ($key eq "Deriver") { $deriver = $value; }
            elsif ($key eq "References") { @references = split ' ', $value; }
        }
        close INFO;

        print "$storePath\n";
        print "$deriver\n";
        print scalar @references, "\n";
        print "$_\n" foreach @references;
    }
}


elsif ($ARGV[0] eq "--substitute") {
    die unless scalar @ARGV == 2;
    my $storePath = $ARGV[1];
    (my $infoFile, my $sourcePath) = findStorePath $storePath;
    print "\n*** Copying `$storePath' from `$sourcePath'\n\n";
    system("nix-store --dump $sourcePath | nix-store --restore $storePath") == 0
        or die "cannot copy `$sourcePath' to `$storePath'";
}


else { die; }